9985

9985 = 5 x 1997.

9985 is the number of hyperbolic knots with 13 crossings (A052408).

9985 is 23401 in base 8.

9985 is a number n such that n, n + 2, n + 4, n + 6, n + 8, n + 10, and n + 12 are all semiprimes (A092129).

9985 is the number of composite numbers between the largest 29-digit prime and the smallest 30-digit prime (A109936).

9985 has two representations as a sum of two squares: 9985 = 24² + 97² = 39² + 92².

9985 is the hypotenuse of two primitive Pythagorean triples: 9985² = 4656² + 8833² = 6943² + 7176².

Source: What's Special About This Number?